Hernias of the Abdominal Wall: Inguinal Anatomy in the Male
Bob Caruthers. CST. PhD
The surgical repair of an inguinal hernia, although one of the in this discussion. The anterolateral group consists of two mus- most common of surgical procedures, presents a special chal- cle groups whose bodies are near the midline and whose fibers lenge: Groin anatomy remains one of the more difficult topics are oriented vertically in the standing human: the rectus abdo- to master for both the entry-level student and the first assistant. minis and the pyramidalis. The muscle bodies of the other This article reviews the relevant anatomy of the male groin. three groups are more lateral, have significantly larger aponeu- roses, and have obliquely oriented fibers. These three groups MAJOR FASClAL AND UGAMENTAL STRUCTURES contribute the major portion of the fascia1 and ligamental The abdominal wall contains muscle groups representing two structures in the groin area.',!.' broad areas: anterolateral and posterior (see Figure 1).The At the level of the inguinal canal, the layers of the abdomi- posterior muscles, the quadratus lumborum, do not concern us nal wall include skin, subcutaneous tissue (Camper's and
aponeurosis (cut edge)
Internal abdominal (cut and turned down)
Lacunar (Gimbernatk) ligament
Inguinal (Poupart k) 11ganenr Cremaster muscle (medial origin)
Cremaster muscle [lateral origin)
Falx inguinalis [conjoined tendon) Cremaster muscle and fascia
Reflected inguinal ligament External spermatic fascia (cut)
Figun, 1-Dissection of rhe anterior ahdominal wall. Rectus sheath (posterior layerl , Inferior epigastric vessels Deep inguinal ring , Transversalis fascia (cut away)
'.,."" -- Rectus abdomlnls muscle \ Antenor-supenor 111acspme \ -. ,lliopsoas muscle
Hesselbach'sl triangle
inguinalis (conjoined) , Tesricular vessels and genital branch of genitofmoral
Scarpa's fascia), external oblique fascia, from the upper six ribs course downward inguinal (Poupart's) ligament. This liga- cremasteric muscle fibers, spermatic obliquely and anteriorly to become the ment marks, in the groin, the separation cord structures, the transversus abdo- external oblique aponeurosis. The between the abdominal wall and the minis aponeurosis, the transversalis fas- aponeurotic fibers from each side inter- lower limb. Hernias that occur immedi- cia, preperitoneal tissues, and peri- lace with fibers from the opposite side ately above this ligament are considered toneum.'.'.' in the linea alba. Fibers of the external to be in the inguinal area, while hernias abdominal oblique fuse with fibers from existing below the ligament are called
EXTERNAL ABDOMINAL OBUQUE the underlying internal abdominal femoral hernias (see Figures 2 and 3). MUSCLE oblique to form the sheath of the rectus The more medial of the rolled-under The external abdominal oblique muscle abdominis muscle.'.:,'.' fibers of the inguinal ligament flatten is the most superficial, thickest, and into a horizontal shelf. These fibers largest of the anterolateral muscle INGUINAL LIGAMENT attach to the os pubis, and this continu- groups. The muscle body is found later- In the groin area, a continuation of the ation of the inguinal ligament is called ally, having a strong, flat aponeurosis aponeurosis of the external abdominal the lacunar (Gimbernat's) ligament. occurring anteriorly. The external oblique stretches from the pubic tuber- The spermatic cord, which courses abdominal oblique muscle arises from cle to the anterior-superior iliac spine. through the inguinal canal, rests on the the lower outside border of the lower This extension is a rolled-under, inferior lacunar ligament until it turns to exit eight ribs. Fibers from the bottom two margin of the aponeurosis of the exter- through the superficial inguinal ring. ribs insert in the iliac crest, while fibers nal abdominal oblique and is called the Fibers that continue laterally along the
26 Fchruarv IYQB Thm Srr#loal T~ohnolo~lst anterior border of the superior ramus of In the upper abdomen, the intemal ic fascia and serves as the middle one of the pubis contribute to the pectineal abdominal oblique aponuerosis splits at the three covering layers oi the cord (Cooper's) ligament.'.'.' the linea sernilunaris, having an anterior and testis (see Figure 4).'.' and posterior sheath. In the lower quar- ter of the abdomen, the aponeurosis does INTERNAL ABDOMINAL OBLIQUE TRANSVERSUS ABDOMlNlS MUSCLE not split, but masses to the midline, MUSCLE The intemal abdominal oblique mus- anterior to the rectus abdominis muscle. The transversus abdominis muscle is the cle-as the middle one of the three flat The lower fibers arch over the spermatic innermost of the flat muscles of the abdominal muscles-is a thin, muscular cord and insert in the superior border of abdomen, having an extensive and var- sheet arising from the posterior layer of the pubis. These fibers join with similar ied origin in the cartilages of the six the thoracolumbar fascia, the anterior fibers from the transversalis tnuscle to lower ribs, the thoracolumbar fascia, the two-thirds of the iliac crest, the lateral form the falx inguinalis.'.',' iliac crest, and the inguinal ligament. two-thirds of the inguinal ligament, and The internal surface of the muscle is the iliacus fascia. Posterior fibers ascend lined by the tranversalis fascia.'.:.' CRENlASLlR MUSCLE AND vertically to the inferior borders of the FASCIA lower 3 or 4 ribs, while the other fibers The cremaster muscle originates from TRANSVERSAUS FASCIA spread fan-like in a forward and medial the inferior margin of the intemal The endoabdominal fascia forms a con- fashion. The ultimate insertion of these abdominal oblique muscle and forms tinuous lining of the abdominal cavity. fibers is the linea alba and the pubic part of the coverings of the cord and When this fascia lies deep to the trans- bone. testis: It underlies the external spermat- versus abdominis muscle. it is labeled
Inferior epigastric vessels /covered by transversalis fascia) Linea alba
External abdominal oblique muscle Transversalis fascia (site of / direct inguinal hernia)
Aponeurosis of external Falx inguinalis (conjohed tendon) abdominal oblique muscle
Trarlsveaus abdominis muscle Crenlaster muscle (medial origin)
Cremaster muscle (lateral origin) lntercrural fibers
Inguina! iPoupart's)ligament
~xternalspermatic fascia on Lacunar IGimbernark) ligament spermatic cord exiting
Superficial inguinal ring Pectineal (Cooperk) ligament
Reflected inguinal ligament / I ' Superficial inguinal ring Lateral crus
Figure 3-Dissecrton of the ~nguinalregion (anrerior vtew). "transversalis fascia." When the canal is the deep inguinal ring found lacunar ligaments; the posterior wall- endoabdominal fascia is incact, no her- above the midpoint of the inguinal liga- sometimes called the "floorn-is formed nia exists; therefore, all hernias in the ment. The deep inguinal ring is not by the transversalis fascia and transver- groin represent a defect in the transver- truly "ring-like," but a finger-like diver- sus abdominis muscle. salis fascia. This fascia is attached to the ticulum of the transversalis fascia. The In the male, the contents of the iliac crest and descends upon the iliac canal is directed lateral to medial, deep inguinal canal include the vas deferens; fascia, serving as the superior fascia of to superficial, and cephalad to caudad, deferential artery and vein; testicular the pelvic diaphragm. The internal exiting at the superficial inguinal ring artery; lymphatics; autonomic nerves; spermatic fascia is the principle out- occurring above and lateral to the pubic the ilioinguinal nerve and genital por- pouching of the transversalis fascia; its tubercle. tion of the genitofemoral nerve; and the mouth is the deep inguinal ring.".' Whereas the superficial boundary of cremaster artery, which is a branch of the canal is formed by the external the inferior epigastric artery.'".'.' INGUINAL CANAL oblique aponeurosis, the most cephalad The inguinal canal is approximately wall is formed by the intemal oblique INFERIOR EPIGASTRIC VESSELS 4-cm long and obliquely oriented; it lies and tranversus muscles, along with The external iliac arteries supply blood 2 cm to 4 cm above and parallel to the aponeurotic fibers from each. The infe- to the legs, and the intemal iliac arteries inguinal ligament. Entrance to the rior wall is formed by the inguinal and supply the pelvis and perineum. The
Ductus (vasl deferens covered by peritoneum Erternal iliac vessels covered by peritoneum Internal abdominal oblique muscle \ Ductus (vas) deferens External abdominal oblique muscle
Inferior epigastric vessels Transversus abdominis muscle
Cremasteric vessels Transversalis fascia
Medial umbilical ligament (obliterated umbilical artery)
Rectus abdominis mcacle Internal spermatic fascia
Superficial inguinal ring
'Spermatic cord
External spermatic fascia \ Femoral vessels enveloping spermatic cord
Cremaster muscle and / \ Inguinal (Poupartk) ligament fascia on sperrnaric cord . . / \:::-. I Figure 4-Spemur~c cord and ~ngulnalcanal
28 Febru~r\I"*S Tho Surgical Toohnoiogist External abdominal
External abdominal Rectus shearh (anterior layer)
Anterior-super~oriliac spine Superficial epigastric vessels
Intercrural fibers Inguinal (Poupartk) ligament
ring
Figure &Femoral and inguinal regions (subcutaneous fascia has been removed). external iliac artery passes under the INGUlNAL HERNIAS The techniques of hernia repair are inguinal ligament at a point midway Several schemes are used to describe her- beyond the scope of this review, but the between the anterior-superior iliac spine nias: One of the more traditional distinc- certified surgical technologist will recog- and the symphysis pubis: At that cross- tions made when referring to inguinal nize that the various methods of repair ing point, it becomes the femoral artery. hernias is that between direct and indirect tend to make use of different ligaments The external iliac artery follows the hernias. The indirect inguinal hernia is to reconstruct an intact and sufficiently medial border of the psoas muscle, giv- characterized by a herniation of abdomi- strong transversalis fascia1 plane.12.'" ing off several branches. The inferior nal contents into an unobliterated vagi- epigastric artery branches from the nal process within the coverings of the REFERENCES external iliac artery just above the spermatic cord that begins at the deep 1. Woodburne RT, Burke1 WE. inguinal ligament and has its origin at inguinal ring. The structures traverse the Essentials of Human Anatomy. 8th ed. the medial border of the deep inguinal inguinal canal to emerge at the superfi- New York, NY: Oxford University ring. The spermatic cord passes behind cial inguinal ring, and the contents may Press, 1988. and lateral to the epigastric artery and descend into the scrotum (see Figure 5). 2. Wantz GE. Open Repuir of Hernias of vein. The direct inguinal hernia, which the Abdominal Wall.Scientific By using three points-the inferior occurs one-third as frequently as the American CD-ROM. Scientific epigastric artery and vein, the symphysis indirect hernia, develops secondarily to a American Inc, 1997. ~ubis,and the rectus abdominis muscle weakness in the superficial inguinal ring 3. Netter E A Guide to the interactive as it reaches the midline of the and the abdominal wall lateral to the Atlas of Human Anatomy. Summit, abdomen-one can create an imaginary falx inguinalis. The inferior epigastric NJ: Ciba-Geigy Corporation, 1995. triangle called "Hesselbach's triangle," artery lies lateral to the mass; that is to 4. Sabiston DC. Textbook of Surgery: which is used to determine whether a say, the mass occurs in Hesselbach's tri- The Biological Basis of Modem Surgical hernia is considered direct or indi- angle. The covering layers of this type of Practice. Philadelphia, Pa: W.B. rect. I.'.' hernia are those of the abdominal wall. Saunders Co, 1997. A